The present invention relates to bearing assemblies, and more particularly to bearing assemblies incorporating a floating seal.
Bearing assemblies are used in a wide variety of applications to generally reduce frictional resistance that occurs during relative movement. The specific type of bearing assembly used is application dependent and may include ball bearings, cylindrical roller bearings, needle bearings, tapered roller bearings, spherical roller bearings, and the like that can be configured to accommodate, for instance, radial loads, thrust loads, or some combination thereof.
Bearing assemblies are often exposed to harsh operating environments. As a result, many bearing assemblies include some form of a seal to prevent contaminants (e.g., dust and debris) from becoming lodged between internal moving parts. Even relatively small particles can have a significant impact on the performance and the useful operating life of a bearing assembly.
Bearing assemblies used in elevated temperature applications (e.g., environments or operating conditions approaching or exceeding approximately 1200 degrees Fahrenheit) are subject to additional demands. Bearing assemblies employed in, for instance, hot gas valve systems (e.g., hot air bleed and regulating valves), valves for ground-based power generation systems, and aircraft air-control systems often operate at elevated temperatures. These elevated temperatures can result in thermal gradients within the bearing assembly and cyclical heating and cooling of the bearing assembly, which in turn cause the various components of the bearing assembly to expand and contract at different rates due to non-uniform coefficients of thermal expansion. Even components having similar coefficients may expand and contract in a manner that negatively impacts the relative placement or arrangement of bearing assembly components. As a result, conventional seal configurations that are intended to inhibit contaminants from fouling the bearing assembly can be degraded or ineffective in elevated temperature applications. Of course, similar detrimental effects can become pronounced in decreased temperature applications.
Other factors may operate independently or in concert with the thermal issues to further impair the functionality of a bearing assembly seal. For instance, the radial/axial forces acting on the bearing assembly can have a tendency to misalign bearing assembly components, which can result in misalignment of the seal. Additionally, forces resulting from movement, shock, and vibration can, at least temporarily, result in misalignment of bearing assembly components (e.g., the seal) such that undesirable contaminants may infiltrate the bearing assembly.
One approach to mitigate contamination resulting from thermal or structural misalignment of the bearing assembly components has been to provide a cover that substantially encases the bearing assembly. While marginally effective in certain applications, the covers have a tendency to complicate the construction and installation of the bearing assembly, require additional cost, impede routine maintenance and service, and may negatively impact the performance of the overall device in which the bearing assembly is a component. In some applications, a relatively limited useful life of bearing assemblies has been accepted as typical, which results in routine repair and/or replacement of worn out bearing assemblies.
In light of at least the above, a need exists for a bearing assembly having an improved design concept that impedes contaminants from negatively impacting the internal bearing assembly components in a variety of scenarios, including elevated temperature applications.